Looks like there are some smaller AGM and lithium-type automotive batteries that can help drop some lbs vs standard replacement batteries. Has anyone here used them? If so, what have you seen re durability, holding charge, etc.? Thx

Most of the smaller AGM batteries are just motorcycle batteries with a post adapter. They also puff up the cranking amps by rating them with a 5 second test vs 15, you can add about 40% to the CCA number when doing it that way.

I have zero experience with the Lithium stuff. All I know is the ones with prismatic cells are supposed to be less likely to catch fire!

I used a half sized battery in my Duster. I fabricated a half size battery tray for it. Worked fine in that car but that car was kept in a heated garage and I had a Denso alternator that held 14 volts at idle.

I run an Odyssey PC925 AGM which is about 1/2 way there in terms of size and weight. 24lbs. I use it because it fits in my gutted repro batt case. 10.2:1 440 Mopar, cranks it over just fine.

In my application it would be going in the trunk-mounted Moroso battery box; don't care what it looks like, only what it works like.

Like you Brad I drive my car to the track and do not have a support vehicle, for that reason I struggle with downsizing a battery. I rely on it to cool the car between passes. I also know from previous mishaps that I can drive my car over an hour with no alternator using a standard yellow top optima.

I run the same Braile battery as pictured above in my race car and have the Odyssey PC25 batteries in my gutted resto battery cases in my street cars.

I have been using a GoLithium 16v battery. No alternator
Im only racing 1/8 and tow up / drive back but it can make it two passes if needed. Most times i am charging it after every pass. It does take about 15? min to charg in that situation. If run down a lot it takes about 30-40 min to fully charge. Works great for a race car and only weights 8 lbs. It can be mounted in passenger compartment so it helps to shorten the wiring and lose even more weight

been using half size AGM batteries for years Odyssey or similar in my Satellite , it is mounted in factory position . Current battery is coming up for 4 years old . It feels like it might be hitting the limit , last one lasted similar , as it now is a hair slower cranking . They often dont give much warning before they die . I have used the same size as Andy but that was ok for 2-3 years but always felt like it was only just enough .


Tex

Street car/ street strip car, I wouldn’t even bother fooling with it. Unlikely it would show up on an ET slip.
I use the biggest honkin interstate battery I can fit in my box, nice 1 wire alternator, and life is good, even running electric fan and water pump going rounds

Most of my cars are street cars that I race....That said, I have tried light weight alternators and batteries...I found neither were enough for street/strip duty with all of todays electronics....I like the red tops a lot and is usually what I use, they are 34lbs....and rated 900ccr

I use a Mechman 170 amp alternator: (best alternator at an idle I have ever used)
https://www.mechman.com/alternators...85-gm-natural-finish-includes-2-pulleys/

And for the big damn Hemi I went to a XS Battery 3400 at 46lbs and rated at 1150ccr
https://www.summitracing.com/parts/xsp-d3400r?seid=srese2&utm_source=bing&utm_medium=cpc&utm_campaign=Brands+|+X&utm_term=4581527515794457&utm_content=GSAPI+5ba2912166b67

I can let the fans run till the motor is cool and fire the car right up...smaller batteries, no way....And the Lithium batteries require a very special charge, and I will not put one in a car. They require constant current till a specific voltage, and then they need switched to low current constant voltage.....I would never just charge one with an alternator, its asking for trouble when over charged. If you don't run an alternator and have a Lithium charger, life is good...But for a street strip car, I have tried many of the lighter batteries, and they just don't have the amps for a big engine.

Biggest Braille battery is 945ccr and 45lbs in AGM form....So not much difference in weight for me....

For what its worth if you run fans and stuff between rounds and you want to run an Optima the Yellow Top is what is best for that. Not that the red one won't work but the yellow is has more cycling capability. Downside is that it is a little heavier and has less CCA on the sticker. My last yellow top lasted 10 years and I only removed it because the seal around the negative post started to let a little gas out and corroded my terminal. I gave it to a friend of uses it on a trailer for a winch.

Full size battery and Chevy 60 amp one wire alternator for this guy.

Snyder motorsports This is what I use

All good info

A lightweight AGM would be my choice; lithium batteries are off the list now

Currently have standard-size Optima Red Top

The idea is to do the smaller battery & fiberglass bumpers w/ aluminum brackets swap at the same time to help offset additional weight gained from switching to the Strange S-60 and some other changes that porked up The MoPig a bit. The driver can stand to get back on a healthier diet and shed some previously-lost weight, as well.

I'm not sure there's a correct answer but if you're really into saving weight of course go with a lithium high voltage and then reduce that to certain components like O2's etc THEN placing that for minimal wire lengths is the ultimate in saving weight. As weight conscious as i was building i decided to stay AGM 12v which actually is heavy at 55lbs. (XS battery) but it has exceptional power and reserve. This is despite some great suggestions from well-accomplished people here. Part of my decision was that i already had all the foundation and battery. A few of my heads-up buddies do the smaller 16V XS 30lb battery and only charge in the pits with no alternator. hope this helps.

I went from an 8.75 to a Dana years ago, saw zip on the slip. This on a car I raced all the time, well sorted.
Gonna be doing same thing with current car, not expecting anything to show up different.

Adding pic

A clamp on amp meter is highly recommended when you start messing with this stuff. You can get a cheap one for $50 or so off Amazon or HoBo Freight.

I used my clamp on to verify the charging amps as well as all of the ground circuits on my Duster. Typically the small battery would recharge in 2 or 3 minutes after a start. I could watch the amp draw fall as the battery charged back up. What I learned with the small battery was that you had to run the engine for a couple of minutes before starting it again or else you could draw it down too far. But the Duster had EFI with coil on plug, high pressure fuel pump, etc. Also EFI was fairly sensitive to cranking volts so I had to be careful to keep the battery charged. Your car will be a little less sensitive to cranking voltage but you'll need to keep an eye on it if you go with a smaller battery.

All my cars have alternators. I used the 13.5 pound dynabatt for many years, hidden inside a gutted restoration battery in my stock appearing gtx, then transfered it later to my street car. I had 2 of them that lasted about 5 years each, and one that went 9 years. I did not have an electric fan or water pump, so starting was all that mattered.

Then in 2017 I switched to lithium. 5 pounds. See my post in Cabs thread. https://board.moparts.org/ubbthread...teries-which-one-to-use.html#Post3098770

I have also used the powersports battery. They work, but don't last too long and are heavier than lithium. About 17 lbs.

I need ballast, however, I appreciate new, viable technology.

Dynabatt fan here. I’ve only had it for a year, but sometimes it sits for a month at a time; lowest voltage has been 12.08. Crank it up and within 5 minutes it’s at 12.8. Price friendly too!

I have been using the Powerlite from Altronics for about 5 years with good results. I have no alternator and it charges up pretty quickly between rounds. Weighs 10 lbs. and it’s 16 volts cranks over my 16-1 small block just fine. Good way to save weight for me. Much better than the 16 volt Turbo Start that I used to use and had to be replaced every year and weighed almost 50 lbs.

Just measured my Optima Red Top... 39.8 lbs. There's an easy 20+ lbs without even going to one of the super small options.

I like Andy's idea of the clamp-on ammeter to do spot-checks on charging characteristics.

Not sure if i agree about your needing ballast. I have a Dakota lithium 60 ah battery that weighs 16 lbs. It delivers the same reserve as a 100ah due to the difference in how the voltage stays up during discharge. It is also 60 amp alternater compatible. With that battery up front, you can dump the long cables to the trunk, saving another 10+ lbs. That would be a minimum reduction of 34 lbs in most cases, more in some. I haven't run it yet, but will in the spring.

as the inner fender below the battery box in my charger is slightly eaten up by acid leaking/gassing, i'm tempted to modify that area to mount a small, lightweight battery, and get rid of the factory mounting tray.
as already said, it would save a bunch of work by not moving the battery into the trunk.
however, what would one do for a cutoff switch at the rear ? a morse cable would work, but what size cable [not the outer sheath] would be appropriate ?
if there was enough room, could the cable possibly be routed along the interior sill plate and pass through the firewall to the front frame rail, and still operate smoothly ?

i have a rear cutoff using a morse cable to the switch up front. Nhra doesn't require a cutoff with a stock battery location up front. No sure on hood requirements

what size cable are you using Greg ?

Originally Posted by moparx
as the inner fender below the battery box in my charger is slightly eaten up by acid leaking/gassing, i'm tempted to modify that area to mount a small, lightweight battery, and get rid of the factory mounting tray.
as already said, it would save a bunch of work by not moving the battery into the trunk.
however, what would one do for a cutoff switch at the rear ? a morse cable would work, but what size cable [not the outer sheath] would be appropriate ?
if there was enough room, could the cable possibly be routed along the interior sill plate and pass through the firewall to the front frame rail, and still operate smoothly ?
beer

i have a rear cutoff using a morse cable to the switch up front. Nhra doesn't require a cutoff with a stock battery location up front. No sure on hood requirements

Exactly what I did. I cut down a repop battery tray, leaving enough room for a cut off switch. Although not required, it is piece of mind to shut off the car's electrical system as needed. Bad pic, but I will post an updates pic later.

Can't remember exactly, maybe 0? About 3/8 fine stranded welding cable. Since everything is up front, a size smaller is ok versus a rear mount cable.

Here are a couple of more pics. Please forgive the wiring mess; I’m changing a few things and haven’t wrapped it back up.